The shares were sold by investment bank UBS at $7 apiece, The Australian reported.
The company confirmed the sale on Wednesday, saying that company founder Ruslan Kogan and his business partner, David Shafer, had "reluctantly accepted the bid due to personal financial commitments”.
The buyer was not mentioned but under ASX rules, the identity of the individual or organisation would have to be revealed in two days.
In a statement to the ASX, the retailer said: "Mr Kogan and Mr Shafer remain fully committed to the business and continue to have the vast majority of their personal wealth invested in Kogan.com.
“Other than the trade outlined above, Mr Kogan and Mr Shafer will not be dealing in securities prior to September 2018.”
At close on Wednesday, the share price was down to $7.31, a fall of about seven per cent.